Determining the Impact of Forest Mortality in Semi-Arid Woodlands on Local and Regional Carbon Dynamics

Principal Investigator:

Litvak, Marcy

Institution:

NEW MEXICO, UNIVERSITY OF

Institution Address:

Albuquerque,
NM
87131-0001

Awarded Amount to Date and B&R Code :

FY 2015

$0 k

FY 2014

$0 k

FY 2013

$349 k

KP170201

FY 2012

$349 k

KP170201

DOE Program Manager:

James Kuperberg

BER Division:

Climate and Environmental Sciences

Research Area:

Terrestrial Ecosystem Science

Abstract Submit Date:

10/09/2013

Project Term:

06/15/2012 - 06/14/2015

Abstract:

The southwestern United States experienced an extended drought from 1999-2002 which led to widespread coniferous tree mortality. Piñon-juniper (PJ) woodlands, which occupy 24 million ha throughout the Southwest, were extremely vulnerable to this drought. An abrupt die-off of 40 to 95% of piñon pine (Pinus edulis) and 2-25% of juniper (Juniperus monosperma) across 1.5 million ha triggered rapid and extensive changes in the structure of PJ woodlands with potentially large, yet unknown, consequences for ecosystem services and feedbacks between the carbon cycle and climate system. Our overarching hypothesis is that coniferous mortality events in PJ woodlands have significant carbon and climate forcing consequences which persist for many decades following mortality. We will take advantage of an existing large-scale manipulation experiment in central New Mexico using paired eddy covariance towers that are directly measuring carbon, water and energy simultaneously over an intact PJ woodland and a disturbed PJ woodland < 5 km away in which ~1600 piñon trees were girdled in 2009 to simulate the mortality observed in 2001-2004. We will augment this experiment and incorporate these findings into a land surface model, DOE’s Community Land Model (CLM) to understand the long term carbon dynamics of these mortality events and use remote sensing maps of mortality in PJ woodlands in NM to scale the implications of these events to regional carbon dynamics and atmospheric CO2. Our specific objectives are: 1) Determine the carbon, water and energy exchange trajectory after mortality in PJ woodlands; 2) Determine the mechanisms controlling the response and recovery of ecosystem production and respiration processes following piñon mortality; 3) Test and improve CLM to work in semiarid ecosystems and represent widespread coniferous mortality; 4) Use CLM to determine long term impacts of widespread mortality on regional level C fluxes and atmospheric CO2. The proposed project has multiple values to science and to DOE. First, one of the glaring questions we face internationally is the climate forcing consequences of vegetation mortality. The estimates from models and observations are currently widespread, which makes modeling the implications of widespread mortality on future carbon and climate forcing difficult. Second, this project is highly cost efficient due to the value-added of the existing three years of data on the results of girdled pine trees, and the wealth of collaborative options with existing remote sensing and modeling efforts on vegetation mortality and its consequences supported at both UNM and LANL. Third, a direct path for input of the results of the experimental and observational data into DOE’s Community Land Model (CLM) is outlined in the proposal.